I would absolutely use a bicycle mode. We already can designate bicycle/walking paths so why not allow navigation for them in a mode that isn't going give bad data to car drivers. Plus how cool would it be to see a little bicycle wazer going by on the map. I use this app for avoiding traffic and road hazards (or plain navigation if I don't know the way somewhere) but a bicycle mode would add additional functionality for me. I'm 30 years old and getting kinda fat I try to ride my bike like every other day because it's helping me get back in shape. Plus the town I live in is HUGE on bike riding so it would get mapped for bicycles in a hurry. Also many other navigation apps to offer these modes so it will help make sure Waze keeps on crushing the competition.

In all honesty, as someone who does databasing I am think the best answer would be to have people give as much information as they can (IF they want nothing annoying but on a settings page or something). That way there is a record of the type of vehicle/usage/speed/restrictions whatever and then with knowing all that information the data could be used to develop new vehicle related features and it would be easy to see what is priority based on number of users in type. Just my humble opinion.